Seroepidemiology: an underused tool for designing and monitoring vaccination programmes in low- and middle-income countries.

Monday, 19th of September 2016

Trop Med Int Health. 2016 Sep;21(9):1086-98. doi: 10.1111/tmi.12737. Epub 2016 Jul 1.

Seroepidemiology: an underused tool for designing and monitoring vaccination programmes in low- and middle-income countries.

Cutts FT¹ Hanson M².

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Abstract

Seroepidemiology the use of data on the prevalence of bio-markers of infection or vaccination is a potentially powerful tool to understand the epidemiology of infection before vaccination and to monitor the effectiveness of vaccination programmes. Global and national burden of disease estimates for hepatitis B and rubella are based almost exclusively on serological data. Seroepidemiology has helped in the design of measles poliomyelitis and rubella elimination programmes by informing estimates of the required population immunity thresholds for elimination. It contributes to monitoring of these programmes by identifying population immunity gaps and evaluating the effectiveness of vaccination campaigns. Seroepidemiological data have also helped to identify contributing factors to resurgences of diphtheria Haemophilus Influenzae type B and pertussis. When there is no confounding by antibodies induced by natural infection (as is the case for tetanus and hepatitis B vaccines) seroprevalence data provide a composite picture of vaccination coverage and effectiveness although they cannot reliably indicate the number of doses of vaccine received. Despite these potential uses technological time and cost constraints have limited the widespread application of this tool in low-income countries. The use of venous blood samples makes it difficult to obtain high participation rates in surveys but the performance of assays based on less invasive samples such as dried blood spots or oral fluid has varied greatly. Waning antibody levels after vaccination may mean that seroprevalence underestimates immunity. This together with variation in assay sensitivity and specificity and the common need to take account of antibody induced by natural infection means that relatively sophisticated statistical analysis of data is required. Nonetheless advances in assays on minimally invasive samples may enhance the feasibility of including serology in large survey programmes in low-income countries. In this paper we review the potential uses of seroepidemiology to improve vaccination policymaking and programme monitoring and discuss what is needed to broaden the use of this tool in low- and middle-income countries.